The purpose of this Mentored Research Scientist Development Award (K01) is threefold. This award will allow me to: 1) learn three new skill sets: geospatial analysis; integrating geospatial techniques with qualitative methodologies; and the use of visual/photographic methods as an adjunct to qualitative research; 2) broaden my understanding of the social epidemiology of HIV among drug users in a new cultural and environmental context (the US/Mexico border); and 3) facilitate my transition to becoming a productive NIH-funded independent investigator at the University of California San Diego. The training aims will be accomplished through a combination of specific workshops and coursework, a hands-on research project, and one-on-one mentoring with a Training Committee comprised of experts in the areas of HIV prevention research among vulnerable populations, GIS and geospatial analysis, mixed methods research, the integration of geospatial and qualitative methodologies, photo-ethnography, ethics, and HIV social epidemiology research in international contexts (and specifically the US/Mexico border region). The research aims will be accomplished by conducting a mixed-methods study of attitudes toward injecting environments and the sociostructural contexts of the use of drugs in particular environments among 60 female sex workers (FSWs) who inject drugs in Tijuana, Mexico. The research project will be conducted as an independent adjunct to an existing NIH/NIDA-funded R01, DA028692-01 (Evolving HIV/STI risk environments of FSWs on the Mexico/US border aka Proyecto Mapa Salud, PI Kimberly Brouwer), in order to capitalize on the infrastructure and expertise represented by that project. The US/Mexico border is experiencing a burgeoning HIV epidemic, concentrated among high-risk groups such as drug users and FSWs. Geospatial and qualitative methods have been used for many years to explore factors associated with the spread of HIV among high risk populations, however emergent methodologies which combine the two have yet to be applied to the study of HIV transmission. Understanding the role of physical space in increasing or decreasing risk associated with injecting drug use, and understanding the social factors which lead already high risk individuals to consume drugs in specific types of location, are critical to improving both individual and community level interventions designed to reduce the spread of infectious disease in border regions. The proposed research will allow me to apply newly acquired skills in geospatial analysis and integrating geospatial techniques with qualitative methods to explore which factors FSW injectors see as 'desirable' and 'undesirable' in an injecting environment, and what social factors in their lives lead them to inject in 'safer' or 'les safe' environments from a public health perspective. This work will be conducted in a particularly high-risk population (in Tijuana, HIV prevalence among those who inject drugs is 4% for men, 10% for women, and 12% for women who also participate in sex work). Findings from the proposed research will be critical for developing tailored interventions for individuals at risk fo HIV via drug use in border regions, and for the development of future research into the role of 'space' in HIV risk. Further, developing skills in geospatial, visual, and mixed geospatial/qualitative methods will uniquely position me as one of only a handful of mixed-methods researchers in the field of drug abuse possessing such skills, and the only one in the Division of Global Public Health at the University of California San Diego.